1. Field of the Invention:
The present invention relates to an outboard motor in which an alternating-current generator or an alternator arranged inside an engine cover can be cooled effectively.
2. Description of the Related Art:
Generally, an outboard motor consists of an engine with a crankshaft disposed vertically, auxiliary machinery and equipment for the engine, and an engine cover covering the engine and the auxiliary machinery and equipment for the engine. The engine cover gives the appearance of the outboard motor.
To the engine is attached an alternating-current generator or an alternator (hereinafter referred to simply as generator) which is driven by the crankshaft through a belt/pulley mechanism. The generator is one of heat sources, and heat liberated by the generator becomes a cause of increased atmospheric temperature in an engine room defined by the engine cover of the outboard motor. The increased atmospheric temperature in the engine room can lead to increased temperature of intake air, resulting in degradation of engine performance. It is thus preferred to cool the generator.
An outboard motor disclosed in, for example, Japanese Patent Laid-Open Publication No. HEI-6-33790, has a generator covered by an engine cover. The generator is, however, provided simply in an engine room and is not cooled. Heat produced by the generator is dissipated in the engine room inside the engine cover, and increases atmospheric temperature in the engine room. Further, in this outboard motor, the generator covered by the cover without being cooled is arranged in the vicinity of a surge tank connected to an intake manifold and a throttle, which may increase temperature of intake air.
Furthermore, the generator provided in the outboard motor according to Japanese Patent Laid-Open Publication No. HEI-6-33790 is covered by the cover that is waterproofed. Hot air dissipated by the generator being driven while the engine is driven, is therefore prevented from being released outside even after a stop of the engine, so that atmospheric temperature in the engine room is not decreased.
It is an object of the present invention to provide an outboard motor which can effectively cool a generator attached to an engine with a simple structure and reliably separate water when letting in air for cooling in such a circumstance as on the sea.
According to an aspect of the present invention, there is provided an outboard motor comprising: an engine with a crankshaft disposed vertically; a generator disposed on the side of the engine and driven via a belt by the crankshaft, the generator having a plurality of slits in its upper and lower portions for letting cooling air in therethrough; an engine cover defining at least part of an engine room housing the engine, and having a front surface, two side surfaces and a top surface integrated with the two side surfaces; an opening provided in the front surface of the engine cover, positioned below the generator in the engine cover, for establishing communication between the inside of the engine cover and the air outside; a first passage provided in the engine cover, communicating with the opening and extending upwards from the position of the opening, for supplying the air from above the generator; and a second passage extending downwards from the position of an upper portion of the first passage, for supplying the air below the generator.
In this arrangement, the first passage for supplying air from above the generator and the second passage for supplying air from below the generator supply cooling air into the upper and lower slits of the generator. The generator being a heat source arranged inside the engine cover of the outboard motor is therefore efficiently cooled.
Desirably, a water separation chamber is further formed in a communicating hole between the first passage and the second passage, for making water and drops of water taken in with the air from the opening, fall. In the outboard motor operated on the waves or with water splashes, water and drops of water enter the inside of the engine cover together with air for cooling the generator, taken in through the opening of the front surface of the engine cover. The water and drops of water are separated from the air in the water separation chamber and made to fall, being prevented from reaching the generator with the air.
In a specific form, the water separation chamber comprises a vertical wall constituting part of a recess having part of the front surface of the engine cover recessed inwards, and a front cover for covering the recess. Since the water separation chamber is formed with the part of the engine cover and the front cover, it can be constructed simply. The front cover is, in an embodiment, for example, screwed to the engine cover in a direction perpendicular to a plane extended between the upper end and the lower end of the front cover.
According to another aspect of the present invention, there is provided an outboard motor comprising: an engine with a crankshaft disposed vertically; a generator driven by the crankshaft via a pulley and a belt; and a belt cover for covering the upper side of the generator, the belt cover having a first opening arranged above and opposed to the pulley of the generator.
In the outboard motor thus arranged, hot air emitted from the generator in operation and left after the engine stops is speedily discharged upwards through the first opening of the belt cover. Thus after a stop of the generator, hot air is prevented from being stagnated around the generator, and the generator and peripheral devices are prevented from being subjected to the effect of heat.
Desirably, the outboard motor further comprises an engine cover having a top surface defining at least part of an engine room housing the engine, for covering an upper portion of the engine, and a front surface continuing from the top surface, the top surface having a second opening formed in a position above the first opening formed in the belt cover. Since the second opening communicating with the first opening is formed in the engine cover, hot air is speedily discharged outside the engine cover.
It is preferred that the front surface of the engine cover has a recess recessed inwards; and the second opening is formed in a step formed in the recess; the second opening comprising a duct having a part extending upwards from a bottom surface of the step. The upwardly extended part separates air and water when the air is taken in, preventing water invasion.
Desirably, the outboard motor further comprises a front cover for covering the recess of the engine cover, the front cover having a plurality of openings in a position lower than the bottom surface of the step, for taking in air therethrough, thereby letting in a sufficient amount of air.
A water drainage may be provided in a position below the bottom surface of the step, thereby speedily draining water entering with air let in.